This invention relates to a display a presenting three dimensional visual effect.
A number of three-dimensional (3D) displays are known. They may be broadly classified into two types: (1) fixed viewing direction ones and (2) real 3D image ones. In a fixed viewing direction display, the 3D image is viewed from one direction only--when the viewer moves around the displayed image, the image does not change. Perspective and binocular displays are examples of fixed viewing direction displays. A real 3D image display permits the viewer to have a side view of the object when moving around the image. That is, the 3D effect is preserved even when the viewer changes the viewing angle. Holography, internal photography, and varifocal mirror displays generate real 3D images.
Tamura et al., Applied Optics 21(20), 3659 (1982), disclose a multilayer 3D display comprising multiple layers of images, in which each image layer is placed at a different optical path length position from a viewing window by a multidirectional beam splitter, to show a composite 3D image.
Buzak, U.S. Pat. No. 4,670,744 (1987), discloses a light reflecting 3D display system. A light source provides a sequence of images, each representing a different depth plane of a subject. Each of the images is selectively reflected from one of a plurality of differently positioned light direction modulators, to synthesize a 3D image of the subject.
Ruderfer, U.S. Pat. No. 2,749,480 (1956), discloses an apparatus for producing 3D visual patterns. The apparatus comprises a plurality of illuminable points or zones determining a cubical or spherical volume. The light points are equipped with electrically operated lamp means and switch means for selectively choosing the lamp means to be actuated.
Additional devices which are of interest because of their multilayered construction but which however are not three dimensional display devices are disclosed by Fergason, WO 86/05282 (1986); Aizawa, U.S. Pat. No. 4,659,182 (1987); Clifford, U.S. Pat. No. 4,448,823 (1984); and Benton, U.S. Pat. No. 4,246,302 (1981).
Fergason discloses a complementary color display device having color layers of encapsulated liquid crystal material, so that light reaching an observer's eyes passes through the layers. By selectively switching the transparency of the colored layers, the observed light is colored or not.
Aizawa discloses a multilayered matrix-type liquid crystal display, comprising front and rear substrates and at least one intermediate substrate interposed therebetween, with liquid crystal layers interposed between the substrates. Switching of the liquid crystal material is effected by intersecting signal and scanning electrodes arranged on opposed mutually facing surfaces of the intermediate and rear substrate and of the intermediate and front substrate. Color layers are arranged in an optical path corresponding to the intersecting portions of the signal and scanning electrodes, but on the opposite side of the intermediate substrate on which the associated intersecting signal and scanning lines are located.
Clifford discloses a multicolored liquid crystal display device, including layered color units. Each colored unit includes either a standard liquid crystal display unit and a colored polarized filter, or a dichroic liquid crystal display unit. By selectively energizing one or more of the liquid crystal displays, display characters of varying colors can be produced.
Benton discloses a multi-band liquid crystal film for visual observation of two or more patterns, prepared by laminating at least two polyurethane films, each containing discrete aggregates of liquid crystals against a black film, such that the visual response of the liquid crystals of each succeeding film is different from that of the other films.
The prior art 3D display devices are disadvantageous in that they are rather bulky, require expensive optics, and/or are unable to present an image which changes or "moves" with time. I have made a three dimensional display device which can generate real 3D images without the need for special glasses or other visual aids, but which is compact and simple to construct. The device of this invention is dynamic, as opposed to static; that is, it can present different 3D images, or even moving 3D images in real time.